-stable review patch. If anyone has any objections, please let us know.
---------------------
From: Andre Przywara <[email protected]>
upstream commit: 1fbdc7a58512a6283e10fd27108197679db95ffa
In the segment descriptor _cache_ the accessed bit is always set
(although it can be cleared in the descriptor itself). Since Intel
checks for this condition on a VMENTRY, set this bit in the AMD path
to enable cross vendor migration.
Cc: [email protected]
Signed-off-by: Andre Przywara <[email protected]>
Acked-By: Amit Shah <[email protected]>
Signed-off-by: Avi Kivity <[email protected]>
Signed-off-by: Chris Wright <[email protected]>
---
arch/x86/kvm/svm.c | 41 +++++++++++++++++++++++++++++------------
1 file changed, 29 insertions(+), 12 deletions(-)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -760,20 +760,37 @@ static void svm_get_segment(struct kvm_v
var->db = (s->attrib >> SVM_SELECTOR_DB_SHIFT) & 1;
var->g = (s->attrib >> SVM_SELECTOR_G_SHIFT) & 1;
- /*
- * SVM always stores 0 for the 'G' bit in the CS selector in
- * the VMCB on a VMEXIT. This hurts cross-vendor migration:
- * Intel's VMENTRY has a check on the 'G' bit.
- */
- if (seg == VCPU_SREG_CS)
+ switch (seg) {
+ case VCPU_SREG_CS:
+ /*
+ * SVM always stores 0 for the 'G' bit in the CS selector in
+ * the VMCB on a VMEXIT. This hurts cross-vendor migration:
+ * Intel's VMENTRY has a check on the 'G' bit.
+ */
var->g = s->limit > 0xfffff;
-
- /*
- * Work around a bug where the busy flag in the tr selector
- * isn't exposed
- */
- if (seg == VCPU_SREG_TR)
+ break;
+ case VCPU_SREG_TR:
+ /*
+ * Work around a bug where the busy flag in the tr selector
+ * isn't exposed
+ */
var->type |= 0x2;
+ break;
+ case VCPU_SREG_DS:
+ case VCPU_SREG_ES:
+ case VCPU_SREG_FS:
+ case VCPU_SREG_GS:
+ /*
+ * The accessed bit must always be set in the segment
+ * descriptor cache, although it can be cleared in the
+ * descriptor, the cached bit always remains at 1. Since
+ * Intel has a check on this, set it here to support
+ * cross-vendor migration.
+ */
+ if (!var->unusable)
+ var->type |= 0x1;
+ break;
+ }
var->unusable = !var->present;
}